Numerical Study of Unsaturated Expansive Soil Canal Slope Covered by Geo-Membrane

2015 ◽  
Vol 744-746 ◽  
pp. 551-554
Author(s):  
Wen Qing Wu ◽  
Jiang Hu Chen ◽  
Hong Yu Zhang ◽  
Jun Hua Wu
Keyword(s):  
Water Content ◽  
Water Level ◽  
Soil Water ◽  
Soil Water Content ◽  
Pore Water Pressure ◽  
Numerical Study ◽  
Water Pressure ◽  
Expansive Soil ◽  
Seepage Field ◽  
Unsaturated Expansive Soil

In view of the holes appearing in different areas of geo-membrane when the geo-membrane technology is applied to the unsaturated expansive soil canal slope, the VADOSE/W is used to analyze the pore-water pressure of the internal canal slope by changing the falling water level. The results show that the hole is nearer to the toe of slope, its effect on the whole seepage field is greater. The greater the rate is, the soil water content is greater.

Stability Analysis of Unsaturated Expansive Soil Slope Covered by Geo-Membrane

2015 ◽  
Vol 744-746 ◽  
pp. 597-600
Author(s):  
Hong Yu Zhang ◽  
Jiang Hu Chen ◽  
Wen Qing Wu ◽  
Jun Hua Wu
Keyword(s):  
Stability Analysis ◽  
Water Content ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Expansive Soil ◽  
Construction Process ◽  
Soil Slope ◽  
Seepage Field ◽  
Lower Slope ◽  
Unsaturated Expansive Soil

In view of the holes appearing in different area of geo-membrane when the geo-membrane technology is applied to the unsaturated expansive soil slope, the VADOSE/W is used to analyze the wetting-drying cycles caused by rainfall and evaporation on slopes covered by geo-membrane. The influence on the pore-water pressure and volume water content were discussed just caused by the holes. The results show that the hole is nearer to the toe of slope, its impact on the whole seepage field is greater. In addition, the hole appears on the top of slope that the wetting-drying cycle effect is remarkable. It is ensured that the integrity of the geo-membrane which in the lower slope and take some drainage measures in the construction process.

scholarly journals Peanut mechanized digging regarding to plant population and soil water level

2014 ◽  
Vol 18 (4) ◽  
pp. 459-465 ◽  
Author(s):  
Cristiano Zerbato ◽  
Vicente F. A. Silva ◽  
Luma S. Torres ◽  
Rouverson P. da Silva ◽  
Carlos E. A. Furlani
Keyword(s):  
Water Content ◽  
Water Level ◽  
Soil Water ◽  
Soil Water Content ◽  
Material Flow ◽  
Block Design ◽  
Plant Population ◽  
Plant Populations ◽  
Randomized Block Design

The largest losses in mechanical harvesting of peanuts occur during the stage of digging, and its assessment is still incipient in Brazil. Therefore, the aim of this study was to evaluate the quantitative losses and the performance of the tractor-digger-inverter, according to soil water content and plant populations. The experiment was conducted in a completely randomized block design with a factorial scheme 2 x 3, in which the treatments consisted of two soil, water content (19.3 and 24.8%) and three populations of plants (86,111, 127,603 and 141,144 plants ha-1), with four replications. The quantitative digging losses and the set mechanized performance were evaluated. The largest amount of visible and total losses was found in the population of 141.144 plants ha-1 for the 19.3% soil water content. The harvested material flow and the tractor-digger-inverter performance were not influenced by soil water content and plant population. The water content in the pods was higher in 24.8% soil water content only for the population of 86,111 plants ha-1; the yield was higher in the populations of 141.144 and 127.603 plants ha-1, in the 19.3 e 24.8% soil water content, respectively.

Optimization Study on Drainage System for Canal of Middle Route Project of SNWT in Expansive Soil Area with High Groundwater Level

2014 ◽  
Vol 580-583 ◽  
pp. 2023-2028
Author(s):  
Hao dong Cui ◽  
Jia Fa zhang ◽  
Guo Sheng zhu ◽  
De Xu Wu ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Water Level ◽  
Groundwater Level ◽  
Water Pressure ◽  
Drainage System ◽  
Expansive Soil ◽  
Control Measures ◽  
Seepage Field ◽  
Finite Element Technology ◽  
North Water ◽  
Soil Area

The seepage field regulation is important for the stability canal liner plate and slope for along the Middle Route of the South-to-North Water Transfer Project, especially for stretches excavated in expensive soil area with groundwater level. In order to analyzing the rationality and efficiency of seepage regulation measures comprehensively, a typical section was modeled, and the seepage field was simulated with the 3D finite element technology. The distribution of seepage field was analyzed and the seepage control measures were compared. The results show that water pressure on the underside of canal pavement would be reduced significantly by the measures, such as the measure of drainage cushion with drainage holes which open just when ground water level is higher than the canal water level, the measure with drainage cushion replaced by the drainage board. The differences among the two kinds of measure were compared. Their application conditions were discussed and proposed.

scholarly journals Experimental and numerical study of upstream slope stability in an earth dam reservoir under rapid drawdown conditions

2020 ◽  
Vol 8 (1) ◽  
pp. 1-15
Author(s):  
Seyed Habib Mousavi Jahromi ◽  
Mansour Pakmanesh ◽  
Amir Khosrojerdi ◽  
Hossein Hassanpour Darvishi ◽  
Hossein Babazadeh
Keyword(s):  
Water Level ◽  
Pore Water Pressure ◽  
Numerical Study ◽  
Water Pressure ◽  
Earth Dam ◽  
Dam Reservoir ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
Seepage Analysis ◽  
Upstream Slope

The rapid ‎drawdown of the dam reservoir is one of the most common situations occurring in the lifetime of a dam. For this reason, one of the main factors in the design of the upstream slope is the rapid drainage of the reservoir. In this case, the upstream slope is in a critical condition and the slope may be unstable. When the water surface in the reservoir is drawdown suddenly, the water level in the dam body does not decrease at the same time as the reservoir water level. The analysis of seepage from the earth dam body and calculation of the water loss play an important role in calculating the amount of pore water pressure, and, consequently, the stability analysis of the dam body. In addition, any seepage analysis is dependent on the hydraulic properties of the dam materials. In order to investigate the effect of hydraulic conductivity on the rapid drawdown of water level and the seepage, an experimental model was constructed of an earth dam. By accurate measurement of hydraulic parameters of the materials in saturated and unsaturated media, the flow through this model was modeled using a disk penetrometer by seep/w software. The results were then compared with the observed data.

scholarly journals Experimental Study on Microstructure of Unsaturated Expansive Soil Improved by MICP Method

2021 ◽  
Vol 12 (1) ◽  
pp. 342
Author(s):  
Xinpei Yu ◽  
Hongbin Xiao ◽  
Zhenyu Li ◽  
Junfeng Qian ◽  
Shenping Luo ◽  
...  
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Cement Content ◽  
Characteristic Curve ◽  
Expansive Soil ◽  
Spherical Particles ◽  
Water Stability ◽  
Soil Water Characteristic Curve ◽  
Engineering Characteristics ◽  
Unsaturated Expansive Soil

The soil water characteristic curve and microstructure evolution of unsaturated expansive soil improved by microorganisms in Nanning, Guangxi were studied by means of filter paper method and scanning electron microscope imaging (SEM). Based on Fredlung & Xing model, the influence law of different cement content on the soil water characteristic curve of improved expansive soil is proved. According to the analysis of SEM test results, the influence mechanism of MICP method on the engineering characteristics of improved expansive soil is revealed. The results show that with the increase of cement content, the saturated water content and residual water content of the improved expansive soil gradually increased. At the same time, the water stability gradually increased while the air inlet value gradually decreased. The improved expansive soil changes from the superposition of flat particles and flake particles to the contact between spherical particles and flake particles, which indicates that the aggregate increases significantly. With the increase of the content of cement solution, the contact between particles tends to be smooth and the soil pores gradually tend to be evenly distributed. The particle size and microstructure of soil particles was changed and the connection between particles was enhanced in the improved expansive soil. Eventually the strength and water stability of expansive soil were improved. The conclusions above not only provide a theoretical basis for the in-depth study of engineering characteristics of unsaturated expansive soil improved by MICP method, but also offer theoretical evidence for perfecting engineering technology of expansive soil improved by MICP method.

scholarly journals Study on Runoff and Infiltration for Expansive Soil Slopes in Simulated Rainfall

Water ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 222
Author(s):  
Wenkai Lei ◽  
Hongyuan Dong ◽  
Pan Chen ◽  
Haibo Lv ◽  
Liyun Fan ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Moisture Content ◽  
Expansive Soil ◽  
Slope Gradient ◽  
Initial Soil Moisture ◽  
Initial Soil

In order to understand the hydrological process of expansive soil slopes, simulated rainfall experiments were conducted to study the effects of slope gradient and initial soil moisture content on runoff and infiltration for expansive soil slopes located in south China. The field program consisted of four neighboring slopes (70%, 47%, 32%, and 21%) instrumented by a runoff collection system and moisture content sensors (EC-5). Results from the monitored tests indicate that there was delay in the response of surface runoff. The runoff initiation time decreased with initial soil water content and increasing slope gradient. After the generation of runoff, the cumulative runoff per unit area and the runoff rate increased linearly and logarithmically with time, respectively. The greater the initial soil moisture content was, the smaller the influence of slope gradient on runoff. A rainfall may contribute from 39% to about 100% of its total rainfall as infiltration, indicating that infiltration remained an important component of the rainwater falling on the slope, despite the high initial soil water content. The larger the initial sealing degree of slope surface was the smaller the cumulative infiltration per unit area of the slope. However, the soil moisture reaction was more obvious. The influence of inclination is no longer discernible at high initial moisture levels. The greater the initial soil moisture content and the smaller the slope gradient, the weaker was the change of soil water content caused by simulated rainfall. The influence of initial soil moisture content and slope gradient on the processes of flow and changes of soil water content identified in this study may be helpful in the surface water control for expansive soil slopes.

Research on the Impact of the Water-Level-Fluctuation Zone on Landslide Stability in the Three Gorges Reservoir Area

2012 ◽  
Vol 188 ◽  
pp. 37-44 ◽  
Author(s):  
Hong De Wang ◽  
Qiang Yang ◽  
Shu Hua Pan ◽  
Wei Cui Ding ◽  
Yong Long Gao
Keyword(s):  
Mechanical Properties ◽  
Water Level ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Physical And Mechanical Properties ◽  
Seepage Field ◽  
Reservoir Water ◽  
Landslide Stability ◽  
The Stability ◽  
The Impact

Taking the Lijiapo landslide in Three Gorges Area as an example, the study on the impact of seepage field changes caused by water level fluctuation on reservoir landslide stability was carried out. In order to find out the variation in slope stability when the reservoir water level changes at different rate, the stability calculation model was established adopting the Seep module and Slope module of Geoscience software GeoStudio, and calibrated with a long sequence of real-time monitoring data, based on the landslide survey data and test data. The results show that the reservoir landslide stability affected by the seepage field changes with changing reservoir level is controlled by a variety of factors, including the hydrodynamic pressure, hydrostatic pressure, uplift force, physical and mechanical properties (с, φ value change). When the water level fluctuates at a high rate, the impact of the seepage field changes on the stability is mainly affected by the pore water pressure before the stability reaches the extremum, while after the extremum, with the further infiltration or drainage of reservoir water, it is mainly affected by the change of physical and mechanical properties. When the water level fluctuates at a lower rate, the pore water pressure, uplift force and physical and mechanical properties are the dominant factors.

scholarly journals Water Level Has Higher Influence on Soil Organic Carbon and Microbial Community in Poyang Lake Wetland Than Vegetation Type

2022 ◽  
Vol 10 (1) ◽  
pp. 131
Author(s):  
Qiong Ren ◽  
Jihong Yuan ◽  
Jinping Wang ◽  
Xin Liu ◽  
Shilin Ma ◽  
...  
Keyword(s):  
Microbial Community ◽  
Organic Carbon ◽  
Carbon Cycle ◽  
Water Content ◽  
Water Level ◽  
Soil Water ◽  
Soil Water Content ◽  
Poyang Lake ◽  
Vegetation Type ◽  
Poyang Lake Wetland

Although microorganisms play a key role in the carbon cycle of the Poyang Lake wetland, the relationship between soil microbial community structure and organic carbon characteristics is unknown. Herein, high-throughput sequencing technology was used to explore the effects of water level (low and high levels above the water table) and vegetation types (Persicaria hydropiper and Triarrhena lutarioriparia) on microbial community characteristics in the Poyang Lake wetland, and the relationships between soil microbial and organic carbon characteristics were revealed. The results showed that water level had a significant effect on organic carbon characteristics, and that soil total nitrogen, organic carbon, recombinant organic carbon, particle organic carbon, and microbial biomass carbon were higher at low levels above the water table. A positive correlation was noted between soil water content and organic carbon characteristics. Water level and vegetation type significantly affected soil bacterial and fungal diversity, with water level exerting a higher effect than vegetation type. The impacts of water level and vegetation type were higher on fungi than on bacteria. The bacterial diversity and evenness were significantly higher at high levels above the water table, whereas an opposite trend was noted among fungi. The bacterial and fungal richness in T. lutarioriparia community soil was higher than that in P. hydropiper community soil. Although both water level and vegetation type had significant effects on bacterial and fungal community structures, the water level had a higher impact than vegetation type. The bacterial and fungal community changes were the opposite at different water levels but remained the same in different vegetation soils. The organic carbon characteristics of wetland soil were negatively correlated with bacterial diversity but positively correlated with fungal diversity. Soil water content, soluble organic carbon, C/N, and microbial biomass carbon were the key soil factors affecting the wetland microbial community. Acidobacteria, Alphaproteobacteria, Verrucomicrobia, Gammaproteobacteria, and Eurotiomycetes were the key microbiota affecting the soil carbon cycle in the Poyang Lake wetland. Thus, water and carbon sources were the limiting factors for bacteria and fungi in wetlands with low soil water content (30%). Hence, the results provided a theoretical basis for understanding the microbial-driven mechanism of the wetland carbon cycle.

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